This disclosure relates generally to linear actuators, and more specifically to integrated motor actuators configured for modular cooling systems, including fluid-cooled devices and other active and passive cooling systems. Suitable applications include, but are not limited to, lightweight, water-cooled linear actuator systems for use in resistance spot welding, and other actively and passively cooled actuator devices configured for automated machine tasks.
Linear actuators are used to control movement and positioning of automated fixtures across a broad range of industrial processes, including automobile assembly, electronics fabrication, machine tooling, materials handling, and in the aerospace, defense, manufacturing and transportation sectors. Generally, rod-style actuators work by extending and retracting a thrust tube with a workpiece or tooling fixture attached to the free end, in order to manipulate industrial components or to perform manufacturing tasks such as a welding and machining. Rodless (carriage or rail-based) positioning systems are also common, and variety of different hydraulic, pneumatic and electric motor drives systems are available depending on desired speed, loading and other operational characteristics.
Integrated motor electric actuators are available with a motor and actuator assembly provided in a single housing structure, for example with the motor driving a screw shaft configured to position a thrust tube assembly with a workpiece connection on the free (external) end. Workpiece fixtures and other rod end connections can be configured to support a variety of different applications, for example a welding gun or other machine tool component.
The screw shaft typically engages a nut coupled with the thrust tube, converting rotary motion of the motor into linear motion of the thrust tube. Alternatively, a drive belt or gearing system can also be used. The motor can either be offset from the screw shaft and coupled via a gear or belt system, or mounted coaxially via a bearing journal assembly. In hollow rotor designs, the stator component can be fixed to the actuator housing with the rotor disposed coaxially about the screw shaft, or extending along a common rotational axis.
Linear actuator design is a complex task, subject to competing requirements for speed, cost, efficiency and service lifetime. Size and weight are also considerations in automated manufacturing applications, where the actuator system is commonly manipulated by an industrial robot arm or similar apparatus. Heating concerns are also relevant, particularly in high-speed, high repetition-rate applications, and where heat must be continuously dissipated from the motor drive and other actuator system components.